This invention relates to combined brake actuators, slack adjustors and locks for railway vehicle brakes, and while the invention is subject to a wide range of applications, a preferred embodiment of the invention will be particularly described as applied to a combined brake actuator, slack adjustor and lock for railway vehicles that is governed by fluid pressure for service brake application and also by operation of a hand brake.
The present invention is particularly useful in a braking systems such as is disclosed, for example, in the Engle U.S. Pat. Nos. 3,508,794 and 3,707,309 which are assigned to the same assignee as is the present invention. These patents, together with my U.S. Pat. No. 3,946,642 are incorporated by reference in the present application. According to the Engle U.S. Pat. No. 3,707,309 braking of a vehicle is selectively rendered effective by fluid braking pressure applied to brake cylinders of the "spread" cylinder type that are suspended horizontally on hangers between tread brakes associated with wheels at each side of a railway truck for longitudinal expansion in response to fluid pressure to apply braking pressures to both wheels on the same side of each railway truck. According to this patent, fluid is applied to the cylinder through a booster which converts input fluid pressure to hydraulic pressure, and includes a hydraulic slack adjustor to automatically adjust for wear in the brake shoes. The "spread" type brake cylinder of my U.S. Pat. No. 3,946,642 is adapted for hand brake operation as well as service brake operation, and includes a fluid controlled lock for mechanically locking a push rod in its braking position. The brake cylinder according to this patent, requires an external slack adjuster device, such as disclosed in the Engle patent as being a part of the booster, for example.
An object of the present invention is to provide an improved combined brake actuator, slack adjuster, and lock for railway vehicle brakes which substantially obviates one or more of the limitations and disadvantages of the described prior art systems.
Another object of the present invention is to selectively apply fluid braking and locking to a push rod within a tubular portion thereof.
Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.